The Sex or Race of Program Directors May Not Play a Significant Role in Impacting Diversity Among Orthopaedic Surgery Residents.

PURPOSE: To identify the influence of residency program characteristics, including the presence of under-represented minorities in medicine (URiM) and/or female program directors (PDs), on the race and sex distribution of orthopaedic surgery residency trainees. METHODS: All active and Accreditation Council for Graduate Medical Education-accredited orthopaedic surgery residency programs from 2017-2021 that reported usable information in the Residency Explorer Tool were included. Data collected included program characteristics, as well as faculty and resident sex distribution, ethnicity, race, and demographic characteristics. The PDs' specific sex, ethnicity, race, and demographic characteristics were collected using residency program websites. The prevalence of factors in programs with the top quartile of female and URiM residents was compared with that in programs with the bottom 3 quartiles. RESULTS: Data were obtained from 148 of 200 Accreditation Council for Graduate Medical Education-accredited programs (3,694 residents). The 52 excluded programs had no usable information in the Residency Explorer Tool or on an identifiable program website. Overall, 15.9% of residents in orthopaedic surgery residency programs were women and 14% were under-represented minorities. The rates of female PDs and chairs were 12.4% and 6.9%, respectively, whereas those of URiM PDs and chairs were 8.3% and 4.6%, respectively. Programs with more female residents were not associated with female PDs (P = .79) or URiM PDs (P = .48). Programs with a greater percentage of URiM residents were not associated with URiM PDs (P = .16). Larger programs (P = .021) and university-based programs (P = .048) had a greater percentage of female residents. Orthopaedic residency programs with visa sponsorship had a greater percentage of URiM residents (P = .017). CONCLUSIONS: Programs with a higher percentage of female or URiM residents did not show a significant association with having female or URiM PDs. Larger programs and university-affiliated programs were more likely to have a larger percentage of female residents, whereas programs that offered visa sponsorship had a higher percentage of URiM residents. CLINICAL RELEVANCE: This study highlights factors influencing diversity among orthopaedic surgery residents. Although the presence of female or URiM PDs does not influence the percentage of female or URiM residents, other program characteristics such as size, affiliation, and visa sponsorship offer potentially actionable insights for promoting greater diversity in orthopaedic training. Doing so may increase under-represented groups within the field and could ultimately impact patient care and improve health care equity.

Achieving Decentralized, Electrified, and Decarbonized Ammonia Production.

The rapid reduction in the cost of renewable energy has motivated the transition from carbon-intensive chemical manufacturing to renewable, electrified, and decarbonized technologies. Although electrified chemical manufacturing technologies differ greatly, the feasibility of each electrified approach is largely related to the energy efficiency and capital cost of the system. Here, we examine the feasibility of ammonia production systems driven by wind and photovoltaic energy. We identify the optimal regions where wind and photovoltaic electricity production may be able to meet the local demand for ammonia-based fertilizers and set technology targets for electrified ammonia production. To compete with the methane-fed Haber-Bosch process, electrified ammonia production must reach energy efficiencies of above 20% for high natural gas prices and 70% for low natural gas prices. To account for growing concerns regarding access to water, geospatial optimization considers water stress caused by new ammonia facilities, and recommendations ensure that the identified regions do not experience an increase in water stress. Reducing water stress by 99% increases costs by only 1.4%. Furthermore, a movement toward a more decentralized ammonia supply chain driven by wind and photovoltaic electricity can reduce the transportation distance for ammonia by up to 76% while increasing production costs by 18%.

Damage Control Surgery and Transfer in Emergency General Surgery.

Selective non traumatic emergency surgery patients are targets for damage control surgery (DCS) to prevent or treat abdominal compartment syndrome and the lethal triad. However, DCS is still a subject of controversy. As a concept, DCS describes a series of abbreviated surgical procedures to allow rapid source control of hemorrhage and contamination in patients with circulatory shock to allow resuscitation and stabilization in the intensive care unit followed by delayed return to the operating room for definitive surgical management once the patient becomes physiologic stable. If appropriately applied, the DCS morbidity and mortality can be significantly reduced.

Energy Management and Economic Considerations of Intermittent Photovoltaic-Driven Electrochemical Ammonia Production.

As the energy sector shifts from fossil fuels to renewable energy, there is a need for long-duration energy storage solutions to handle the intermittency of renewable electricity. Electrofuels, or fuels synthesized from excess electricity, are an emerging medium poised to meet long-duration energy storage requirements. Ammonia as an electrofuel is potentially ideal because ammonia has a relatively low liquefaction pressure, indicating that ammonia can be easily stored and transported. Here, we develop a framework to optimize the electrochemical production of ammonia powered by intermittent photovoltaic power. We also explore various buyback policies to understand the impact that policy has on the cost of intermittent ammonia and optimal sizing ratios. The optimal ratio of the photovoltaic to the electrolyzer is ∼3.7 MWPV/MWELEC for a system that is completely powered by renewable photovoltaic power and operates intermittently. The optimal ratio of the photovoltaic to the electrolyzer is ∼3.3 MWPV/MWELEC for a system that uses photovoltaics in conjunction with grid electricity and operates continuously. For the purchase price at the avoided cost of electricity, the optimal ratio of the solar panel to the electrolyzer increases to ∼4 MWPV/MWELEC for a system that can only sell to the grid and ∼5 MWPV/MWELEC for a system that can buy and sell electricity to the grid at the avoided cost. Optimizing energy management by setting auxiliary battery size limits is essential to reducing ammonia costs, and the optimal battery size decreases as the buyback price of electricity increases. Finally, we find that systems connected to the grid and operating continuously have emissions comparable to the Haber-Bosch process because of the current emissions tied to the United States electricity generation. Thus, unless the grid is completely decarbonized, it is essential to create electrofuels that rely minimally on grid electricity.

Access to Total Knee Arthroplasty for Military Insured Patients.

Background: Rigorous training may lead to increased rates of knee osteoarthritis and arthroplasties in military service members. Given the large numbers of arthritis and the increasing need for total joint replacements, access to appropriate care can be difficult for this population based on insurance restrictions. The aim of this study was to evaluate access to total knee arthroplasty for TRICARE patients in contracted civilian medical facilities. Methods: Orthopedic surgeons contracted to perform total knee replacements in the state of Florida were identified via TRICARE's website. Investigators used a secret shopper methodology with a standardized script to request an appointment for their family member for a total knee arthroplasty using either TRICARE Select or BlueCross preferred provider organization. The appointment acceptance rates, wait times, call duration, and accuracy of the physician listing were collected. Results: A total of 228 offices that perform total knee arthroplasties in Florida were successfully contacted. Overall, 43.1% of the clinics had an inaccurate online listing, and 207 (91%) were able to schedule an appointment with TRICARE, compared to 93% for BlueCross Blue Shield (P = .06). The average wait for TRICARE patients was 24 days and 18 days for BlueCross (P < .01). Call times for TRICARE patients averaged 7.2 minutes, compared to 5.2 minutes for BlueCross (P < .01). Conclusions: TRICARE patients encountered longer waiting periods and inaccurate provider listings when accessing orthopedic care. Our results suggest a disparity in healthcare access for patients using TRICARE, which may result in negative health outcomes from receiving delayed care.

Toward Self-Healing Concrete Infrastructure: Review of Experiments and Simulations across Scales.

Cement and concrete are vital materials used to construct durable habitats and infrastructure that withstand natural and human-caused disasters. Still, concrete cracking imposes enormous repair costs on societies, and excessive cement consumption for repairs contributes to climate change. Therefore, the need for more durable cementitious materials, such as those with self-healing capabilities, has become more urgent. In this review, we present the functioning mechanisms of five different strategies for implementing self-healing capability into cement based materials: (1) autogenous self-healing from ordinary portland cement and supplementary cementitious materials and geopolymers in which defects and cracks are repaired through intrinsic carbonation and crystallization; (2) autonomous self-healing by (a) biomineralization wherein bacteria within the cement produce carbonates, silicates, or phosphates to heal damage, (b) polymer-cement composites in which autonomous self-healing occurs both within the polymer and at the polymer-cement interface, and (c) fibers that inhibit crack propagation, thus allowing autogenous healing mechanisms to be more effective. In all cases, we discuss the self-healing agent and synthesize the state of knowledge on the self-healing mechanism(s). In this review article, the state of computational modeling across nano- to macroscales developed based on experimental data is presented for each self-healing approach. We conclude the review by noting that, although autogenous reactions help repair small cracks, the most fruitful opportunities lay within design strategies for additional components that can migrate into cracks and initiate chemistries that retard crack propagation and generate repair of the cement matrix.

The Relationship Between an Individual's Birthday and Admission for Traumatic Injury.

BACKGROUND: Birthdays provide an opportunity to celebrate; however, they can also be associated with various adverse medical events. This is the first study to examine the association between birthdays and in-hospital trauma team evaluation. METHODS: This retrospective study analyzed trauma registry patients 19-89 years of age, who were evaluated by in-hospital trauma services from 1/1/2011 to 12/31/2021. RESULTS: 14,796 patients were analyzed and an association between trauma evaluation and birthdays was found. The strongest incidence rate ratios (IRRs) were on the day of birth (IRR: 1.78; P < .001) followed by ±3 days of the birthday (IRR: 1.21; P = .003). When incidence was analyzed by age groups, 19-36 years of age had the strongest IRR (2.30; P < .001) on their birthday, followed by the >65 groups (IRR: 1.34; P = .008) within ±3 days. Non-significant associations were seen in the 37-55 (IRR: 1.41; P = .209) and 56-65 groups (IRR: 1.60; P = .172) on their birthday. Patient-level characteristics were only significant for the presence of ethanol at trauma evaluation (risk ratio: 1.83; P = .017). DISCUSSION: Birthdays and trauma evaluations were found to have a group-dependent association, with the greatest incidence for the youngest age group being on their birthday, and the oldest age group within ±3 days. The presence of alcohol was found to be the best patient-level predictor of trauma evaluation.

The Impact of Relocating a Trauma Center: Observations on Patient Injury Demographics and Resident Volumes.

Introduction Changing the physical zip code location of an academic trauma center may affect the distribution and surgical volume of its trauma patients. General surgical residency case log requirements may also be affected. This study describes the impact of moving a level I trauma center to a different zip code location, on the hospital and resident trauma case volumes. Methods This retrospective analysis included all patients within the local trauma registry across two fiscal years representing the pre- and post-move timeframes. Variables collected included patient basic sociodemographic and injury information, trauma activation level and transfer status, management (operative management [OPM] versus non-operative management [NOPM]), and resident case logs. Results During fiscal years 2016-2017 and 2017-2018, 3,025 patients were included. Pre-move and post-move trauma volumes were 1,208 and 1,817 respectively. Post-move changes demonstrated differences in basic sociodemographics, with differences in age (six years older), a shift toward white and away from black (12.89%), and males being seen more frequently (11.87%). Injury severity score distribution shifted (7.72%) towards less severe trauma scores (<15), the percentage of patients with blunt trauma (4.19%) and falls increased (ground level and greater than 1 meter, 9.78%) while the number of patients considered full activations were decreased (15.67%). Proportions of OPM and NOPM trauma cases remained unchanged with the exception of a reduction in emergent operative trauma (3.1%). Resident case logs requirements were met both pre- and post-move. Conclusion Relocating the trauma center to a different zip code location did not negatively impact our resident case volumes. Total trauma volumes were increased, with a shift in the demographics and severity distribution of injuries.

Takotsubo Cardiomyopathy and Trauma: The Role of Injuries as Physical Stressors.

INTRODUCTION: Physical stressors are common predisposing factors for takotsubo cardiomyopathy (TTC). However, the role of traumatic injuries in TTC has not been well defined. This study describes the characteristics of TTC in the broad spectrum of traumatic injuries using the information available in the National Trauma Data Bank (NTDB). MATERIALS AND METHODS: This retrospective study analyzed trauma patients ≥ 18 years old in the NTDB, from 2007 to 2018, with a diagnosis of TTC. RESULTS: A total of 95 TTC diagnoses were found. The median age was 68 years old (interquartile range: 55-80). Patients were predominantly female (67.4%), white (88.4%), and sustained blunt mechanisms of injury (90.5%). Penetrating trauma was most common in males (16%). Most diagnoses were related to extremity trauma (53.7%), followed by head injury (26.3%). The most common severity scores were Glasgow Coma Scale (GCS) > 13 or < 8, and Injury Severity Score (ISS) < 15 or > 25. Males more commonly presented with GCS < 8 (68%), ISS > 25 (33%), high intensive care unit (ICU) admission rate (77.4%), and mechanical ventilation (51.6%). The median duration of the mechanical ventilation was eight days for both sexes. The ICU length of stay (LOS) was six days with a hospital LOS of nine days and a trend toward a longer LOS in males. The in-hospital mortality rate was 11.7% for both sexes. CONCLUSIONS: TTC in traumatic injuries is common at both ends of the severity spectrum and has different sex distribution. TTC patients are predominantly females and have more commonly extremity trauma than head injury. Males are more severely injured and under mechanical ventilation.

In-hospital outcomes of intercostal nerve cryoablation and surgical stabilization of rib fractures.

BACKGROUND: Severe pain and pulmonary complications commonly follow rib fractures, both of which may be improved by surgical stabilization of rib fractures (SSRFs). However, significant postoperative pain still persists which may negatively impact in-hospital outcomes. Combining intercostal nerve cryoablation (INCA) with SSRF may improve those outcomes by further decreasing postoperative pain, opioid consumption, and pulmonary complications. The hypothesis is that INCA plus SSRF reduces opioids consumption compared with SSRF alone. METHODS: The retrospective analysis included trauma patients 18 years or older who underwent SSRF, with or without INCA, in a Level I trauma center between 2015 and 2021. Patients received INCA at the surgeons' discretion based on familiarity with the procedure and absence of contraindications. Patients without INCA were the historical control group. Reported data include demographics, mechanism and severity of injury, number of ribs stabilized, cryoablated nerves, intubation rates and duration of mechanical ventilation. The primary outcome was total morphine milligrams equivalent consumption. Secondary outcomes were intensive care unit length of stay, hospital length of stay, incidence of pneumonia, and tracheostomy rates, and discharge disposition. Long-term outcomes were examined up to 6 months for adverse events. RESULTS: Sixty-eight patients were included, with 44 receiving INCA. There were no differences in rates of pneumonia ( p = 0.106) or duration of mechanical ventilation ( p = 0.687), and hospital length of stay was similar between groups ( p = 0.059). However, the INCA group demonstrated lower total morphine milligrams equivalent ( p = 0.002), shorter intensive care unit length of stay ( p = 0.021), higher likelihood of home discharge ( p = 0.044), and lower rate of intubation ( p = 0.002) and tracheostomy ( p = 0.032). CONCLUSION: Combining INCA with SSRF may further improve in-hospital outcomes for patients with traumatic rib fractures. LEVEL OF EVIDENCE: Therapeutic/Care Management; Level III.

Síndrome coronario agudo e insuficiencia mitral-aórtica grave en un paciente con rubeola congénita / Acute coronary syndrome and mitral-aortic insufficiency in a patient with congenital rubella

Resumen La rubeola es una enfermedad exantemática que se produce en la infancia. En caso de que se presente durante la gestación y hubiera afectación del producto, este puede desarrollar el síndrome de rubeola congénita, el cual incluye malformaciones cardiacas que se presentan en el 67% de los pacientes, de las cuales la más común es la persistencia del conducto arterioso, seguida de la estenosis valvular pulmonar y la comunicación interauricular. Se presenta el caso de un hombre de 20 años con diagnóstico de síndrome de rubeola congénita, quien desarrolló glaucoma congénito, insuficiencia aórtica grave, insuficiencia mitral grave y enfermedad miocárdica isquémica. Se realizó procedimiento quirúrgico de revascularización coronaria y recambio valvular mitral y aórtico. Los estudios encontrados durante el proceso de investigación mencionan el daño de los vasos sanguíneos y del miocardio producido por el virus. Con los datos obtenidos se corrobora la baja incidencia de presentación con compromiso coronario y valvular, por lo cual se hace énfasis en la importancia de este caso.

Abstract Rubella is an exanthematous disease that occurs in childhood. If it occurs during pregnancy and there is an effect on the product, it can develop congenital rubella syndrome. The congenital rubella syndrome includes cardiac malformations, which occur in 67% of patients, of which the most common is patent ductus arteriosus, followed by pulmonary valvular stenosis and atrial septal defect. We present the case of a 20-year-old man with a diagnosis of congenital rubella syndrome, presenting with congenital glaucoma, severe aortic insufficiency, severe mitral regurgitation and ischemic myocardial disease. In which a surgical procedure is performed by a coronary revascularization and mitral and aortic valve replacement. Studies found during the research process mention the damage to the blood vessels and myocardium produced by the virus. With the required data, the low incidence of presentation with coronary and valvular involvement is corroborated, which is why the importance of the present case is emphasized.

A systematic review of penetrating extracranial vertebral artery injuries.

BACKGROUND: Penetrating vertebral artery injuries (VAIs) are rare. Because of their rarity, complex anatomy, and difficult surgical exposures, few surgeons and trauma centers have developed significant experience with their management. The objectives of this study were to review their incidence, clinical presentation, radiologic identification, management, complications, and outcomes and to provide a review of anatomic exposures and surgical techniques for their management. METHODS: A literature search on MEDLINE Complete-PubMed, Cochrane, Ovid, and Embase for the period of 1893 to 2018 was conducted. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were used. Our literature search yielded a total of 181 potentially eligible articles with 71 confirmed articles, consisting of 21 penetrating neck injury series, 13 VAI-specific series, and 37 case reports. Operative procedures and outcomes were recorded along with methods of angiographic imaging and operative management. All articles were reviewed by at least two independent authors, and data were analyzed collectively. RESULTS: There were a total of 462 patients with penetrating VAIs. The incidence of VAI in the civilian population was 3.1% vs 0.3% in the military population. More complete data were available from 13 collected VAI-specific series and 37 case reports for a total of 362 patients. Mechanism of injury data were available for 341 patients (94.2%). There were gunshot wounds (178 patients [49.2%]), stab wounds (131 [73.6%]), and miscellaneous mechanisms of injury (32 [8.8%]). Anatomic site of injury data were available for 177 (49%) patients: 92 (25.4%) left, 84 (23.2%) right, and 1 (0.3%) bilateral. Anatomic segment of injury data were available for 204 patients (56.4%): 28 (7.7%) V1, 125 (34.5%) V2, and 51 (14.1%) V3. Treatment data were available for 212 patients. Computed tomography angiography was the most common imaging modality (163 patients [77%]). Injuries were addressed by operative management (94 [44.3%]), angiography and angioembolization (72 [34%]), combined approaches (11 [5.2%]), and observation (58 [27.4%]). Stenting and repair were less frequently employed (10 [4.7%]). The incidence of aneurysms or pseudoaneurysms was 18.5% (67); the incidence of arteriovenous fistula was 16.9% (61). The calculated mortality in VAI-specific series was 15.1%; in the individual case report group, it was 10.5%. CONCLUSIONS: The majority of VAIs present without neurologic symptoms, although some may present with exsanguinating hemorrhage. Computed tomography angiography should be considered first line to establish diagnosis. Gunshot wounds account for most injuries. The most frequently injured segment is V2. Surgical ligation is the most common intervention, followed by angioembolization, both of which constitute important management approaches.

The Role of miR-126 in Critical Limb Ischemia Treatment Using Adipose-Derived Stem Cell Therapeutic Factor Concentrate and Extracellular Matrix Microparticles.

BACKGROUND Paracrine factors secreted by adipose-derived stem cells can be captured, fractionated, and concentrated to produce therapeutic factor concentrate (TFC). The present study examined whether TFC effects could be enhanced by combining TFC with a biological matrix to provide sustained release of factors in the target region. MATERIAL AND METHODS Unilateral hind limb ischemia was induced in rabbits. Ischemic limbs were injected with either placebo control, TFC, micronized small intestinal submucosa tissue (SIS), or TFC absorbed to SIS. Blood flow in both limbs was assessed with laser Doppler perfusion imaging. Tissues harvested at Day 48 were assessed immunohistochemically for vessel density; in situ hybridization and quantitative real-time PCR were employed to determine miR-126 expression. RESULTS LDP ratios were significantly elevated, compared to placebo control, on day 28 in all treatment groups (p=0.0816, p=0.0543, p=0.0639, for groups 2-4, respectively) and on day 36 in the TFC group (p=0.0866). This effect correlated with capillary density in the SIS and TFC+SIS groups (p=0.0093 and p=0.0054, respectively, compared to placebo). A correlation was observed between miR-126 levels and LDP levels at 48 days in SIS and TFC+SIS groups. CONCLUSIONS A single bolus administration of TFC and SIS had early, transient effects on reperfusion and promotion of ischemia repair. The effects were not additive. We also discovered that TFC modulated miR-126 levels that were expressed in cell types other than endothelial cells. These data suggested that TFC, alone or in combination with SIS, may be a potent therapy for patients with CLI that are at risk of amputation.

Liver-Directed Embolization for the Long-Term Control of Hypercalcemia of Malignancy in Metastatic Breast Cancer.

Hypercalcemia of malignancy is a common complication of certain types of cancers. No standard therapies exist for the treatment of hypercalcemia secondary to paraneoplastic syndromes that result in the long-term control of serum calcium levels. We report a case of metastatic breast cancer with parathyroid hormone-related protein associated with hypercalcemia of malignancy that was treated with transarterial embolization of the hepatic metastatic lesions.

Stabilization and prolonged reactivity of aqueous-phase ozone with cyclodextrin.

Recalcitrant organic groundwater contaminants, such as 1,4-dioxane, may require strong oxidants for complete mineralization. However, their efficacy for in-situ chemical oxidation (ISCO) is limited by oxidant decay and reactivity. Hydroxypropyl-ß-cyclodextrin (HPßCD) was examined for its ability to stabilize aqueous-phase ozone (O3) and prolong oxidation potential through inclusion complex formation. Partial transformation of HPßCD by O3 was observed. However, HPßCD proved to be sufficiently recalcitrant, because it was only partially degraded in the presence of O3. The formation of a HPßCD:O3 clathrate complex was observed, which stabilized decay of O3. The presence of HPßCD increased the O3 half-life linearly with increasing HPßCD:O3 molar ratio. The O3 half-life in solutions increased by as much as 40-fold relative to HPßCD-free O3 solutions. Observed O3 release from HPßCD and indigo oxidation confirmed that the formation of the inclusion complex is reversible. This proof-of-concept study demonstrates that HPßCD can complex O3 while preserving its reactivity. These results suggest that the use of clathrate stabilizers, such as HPßCD, can support the development of a facilitated-transport enabled ISCO for the O3 treatment of groundwater contaminated with recalcitrant compounds.

A novel description of a syndrome consisting of 7q21.3 deletion including DYNC1I1 with preserved DLX5/6 without ectrodactyly: a case report.

BACKGROUND: Chromosomal region 7q21.3 comprises approximately 5.2 mega base pairs that include genes DLX5/6, SHFM1, and DYNC1I1 associated with split hand/split foot malformation 1. So far, there are reports of eight families with deletion of DYNC1I1 and preserved DLX5/6 associated with ectrodactyly. From these families, only three patients did not present ectrodactyly and, unlike our patient, no other cases have been described as having craniofacial dysmorphology, mitral valve prolapse, kyphoscoliosis, inguinal herniae, or personality disorder. There is no designation described in the literature for patients with syndromic manifestations without ectrodactyly, which hinders diagnosis. CASE PRESENTATION: We report the case of a 44-year-old mestizo (combined European and Amerindian descent) man with a 3191 kilo base pairs deletion and International System for Human Cytogenetic Nomenclature array 7q21.3 (93,389,222-96,579,845)x1. Clinical manifestations included micrognathia, retrognathia, wormian bones, auditory canal stenosis, depressed nasal bridge, epicanthal fold, fullness of upper eyelid, long philtrum, low-set ears, sensorineural hearing loss, kyphoscoliosis, bilateral inguinal herniae, mild mitral valve prolapse, and paranoid personality disorder. His isolated DNA was analyzed using a CytoScan HD Microarray system. Chromosome Analysis Suite software was utilized for the microarray analysis. All copy number changes were determined using the human genome build 19 (hg19/NCBI build 37). CONCLUSIONS: Cases of deletions within chromosome 7q21.3 that include the split hand/split foot malformation 1 region represent a diagnostic challenge when not presenting ectrodactyly despite being syndromic. Due to the heterogeneity of the region, a better method to group and classify these patients is needed to facilitate their clinical diagnosis. For this purpose, we suggest that patients with 7q21.3 deletion including DYNC1I1 and preserved DLX5/6 without ectrodactyly, accompanied by craniofacial dysmorphology, personality disorder, hearing loss, musculoskeletal disorder, inguinal herniae and/or mitral valve prolapse be referred to by the eponym Ramos-Martínez syndrome.

Numerical Simulation of Permeability Change in Wellbore Cement Fractures after Geomechanical Stress and Geochemical Reactions Using X-ray Computed Tomography Imaging.

X-ray microtomography (XMT) imaging combined with three-dimensional (3D) computational fluid dynamics (CFD) modeling technique was used to study the effect of geochemical and geomechanical processes on fracture permeability in composite Portland cement-basalt caprock core samples. The effect of fluid density and viscosity and two different pressure gradient conditions on fracture permeability was numerically studied by using fluids with varying density and viscosity and simulating two different pressure gradient conditions. After the application of geomechanical stress but before CO2-reaction, CFD revealed fluid flow increase, which resulted in increased fracture permeability. After CO2-reaction, XMT images displayed preferential precipitation of calcium carbonate within the fractures in the cement matrix and less precipitation in fractures located at the cement-basalt interface. CFD estimated changes in flow profile and differences in absolute values of flow velocity due to different pressure gradients. CFD was able to highlight the profound effect of fluid viscosity on velocity profile and fracture permeability. This study demonstrates the applicability of XMT imaging and CFD as powerful tools for characterizing the hydraulic properties of fractures in a number of applications like geologic carbon sequestration and storage, hydraulic fracturing for shale gas production, and enhanced geothermal systems.

Redox-Active Metal-Organic Composites for Highly Selective Oxygen Separation Applications.

A redox-active metal-organic composite material shows improved and selective O2 adsorption over N2 with respect to individual components (MIL-101 and ferrocene). The O2 sensitivity of the composite material arises due to the formation of maghemite nanoparticles with the pore of the metal-organic framework material.

Hydrophobic and moisture-stable metal-organic frameworks.

Metal-organic frameworks (MOFs) have proved to be very attractive for applications including gas storage, separation, sensing and catalysis. In particular, CO(2) separation from flue gas in post-combustion processes is one of the main focuses of research among the scientific community. One of the major issues that are preventing the successful commercialization of these novel materials is their high affinity towards water that not only compromises gas sorption capacity but also the chemical stability. In this paper, we demonstrate a novel post-synthesis modification approach to modify MOFs towards increasing hydrophobic behaviour and chemical stability against moisture without compromising CO(2) sorption capacity. Our approach consists of incorporating hydrophobic moieties on the external surface of the MOFs via physical adsorption. The rationale behind this concept is to increase the surface hydrophobicity in the porous materials without the need of introducing bulky functionalities inside the pore which compromises the sorption capacity toward other gases. We herein report preliminary results on routinely studied MOF materials [MIL-101(Cr) and NiDOBDC] demonstrating that the polymer-modified MOFs retain CO(2) sorption capacity while reducing the water adsorption up to three times, with respect to the un-modified materials, via an equilibrium effect. Furthermore, the water stability of the polymer-functionalized MOFs is significantly higher than the water stability of the bare material. Molecular dynamic simulations demonstrated that this equilibrium effect implies a fundamental and permanent change in the water sorption capacity of MOFs. This approach can also be employed to render moisture stability and selectivity to MOFs that find applications in gas separations, catalysis and sensing where water plays a critical role in compromising MOF performance and recyclability.

Separation of polar compounds using a flexible metal-organic framework.

A flexible metal-organic framework constructed from a flexible linker is shown to possess the capability of separating mixtures of polar compounds (propanol isomers) by exploiting the differences in the saturation capacities of the constituents. Transient breakthrough simulations show that these sorption-based separations are in favor of the component with higher saturation capacity.